Short range, wireless transmission of audio is an established and convenient manner for users to listen to sound sources such as television, stereo and computer multimedia devices without disturbing others. Typically, such privacy listening systems employ one or two earphones mounted into a headset that contains the receiver circuitry and power supply.
Generally, wireless communication systems use one of acoustic, radio frequency, infrared, and inductive techniques for short range transmission of audio. Radio frequency and infrared signal transmission are most commonly used for such short range transmission; however, magnetic induction is also used as described in U.S. Pat. No. 5,774,791 to Strohallen et al., entitled “Low Power Wireless Communication System Employing Magnetic Control Zones,” issued 30 Jun. 1998.
As described in U.S. Pat. No. 5,774,791, a receiver configured as a behind the ear (BTE) hearing aid, an in the ear (ITE) hearing aid, or as a cordless headset is described. A transmitter unit, which may include a microphone for picking up external sounds, modulates audio sound to drive a magnetic transmission element, e.g., a neck loop, for transmission to the receiver. The receiver, which includes a magnetic receiving element, demodulates the received signal to provide a sound output to the user. In one embodiment of U.S. Pat. No. 5,774,791, a headset which includes the receiver containing the magnetic receiving element, also may include an infrared (IR) transmitter for transmitting signals back to a base station for two-way communication.
Various types of phones are available, such as cordless phones, cordless cellular phones, corded phones, etc. In particular, cellular phone usage has increased dramatically over the years. Most hand-held radiotelephones, such as mobile phones, or cordless telephones are designed to assume at least the size of a conventional handset during operation, e.g., a fixed handset configuration or a flip phone configuration, with the antenna being in close proximity to the user's head. Recently, health concerns over cell phone radiation and the safety concerns over use of the cell phones while driving (e.g., desire for hands free operation) invite significant new development in this technology.
Several earpiece receivers have been described for phones even though the generally sizeable circuitry and battery power requirements for IR receivers pose a significant challenge to subminiaturization and have generally precluded the use of a comfortable and convenient subminiature earpiece. For example, U.S. Pat. No. 5,881,149 to Weatherill, entitled “Portable Communications Device With Wireless Transmitter and Detachable Earpiece Including a Wireless Receiver,” issued 9 Mar. 1999, describes a portable communication device, i.e., a phone, having a detachable receiver part which can be placed against the ear for use. The portable communications device has an integral transmitter for communicating with the detachable receiver part. Further, U.S. Pat. No. 5,966,643 to Radley, entitled “Hand-Held Radiotelephone Having Two-Part Construction,” issued 12 Oct. 1999, describes a radiotelephone having an earpiece that is spatially separated from the other components of the radiotelephone and includes an IR receiver. The housing of the handheld radiotelephone includes an IR transmitter, i.e., the transmitter is integral with the radiotelephone.
It will be recognized that in each example, the transmitter is integral with the phone. As such, the external wireless earpiece receiver will only function with a particular type of phone.
Further, IR systems have been criticized for being restricted to line of sight communications. While line of sight communications provide for a relatively secure communication link, IR communications have been described as requiring considerable power. For example, the amount of power required by an IR receiver is generally proportional to the ambient light conditions in the user area and the range or distance from the transmitter. Thus, as the ambient light level increases, the power that is needed generally increases. In a like manner, as the range or distance from the transmitter to the receiver increases the power required also increases.